Principle of Pressure-Sensitive Adhesives
Definition
PSAs achieve bonding at room temperature with light pressure and can be repeatedly applied and removed.
Historical Background
1920s: 3M engineer Richard Drew invented masking tape for automotive painting, launching the PSA revolution.
Example
Transparent tape: no heating needed, just press. PSAs have shape-memory, flowing to fill micro-voids then recovering when peeled, like plasticine.
Formula
Adhesion = Tackifying Component + Elastic Component
Core Concepts
Viscoelastic balance: too tacky leaves residue, too elastic fails to stick. Determined by Tg between -20C and +20C.
Extended Applications
Medical: bandages; electronic: smartphone screens; industrial: pipeline anti-corrosion (30-year); automotive: interior trim (80C).